Cyrtandra kamoolaensis is a shrub growing to approximately 2 meters in height. Its stems are rounded to angular and covered with a fine pubescence. The leaves are simple and arranged oppositely, with elliptic blades measuring 9–15 cm in length and 4–8 cm in width. Leaf apices are acuminate, and the bases are cuneate both above and below. Surfaces are puberulous, and the margins may be either entire or toothed. Petioles are 1–4.5 cm long, pubescent, and can sometimes clasp the stem or appear perfoliate. Stipules are absent. The flowers are bisexual (perfect) and borne singly or in cymes 4–5 cm long, typically arising from the upper leaf axils. The inflorescences can be either pedunculate or sessile, with peduncles bearing bracts that range from minute to large and foliaceous—these bracts may be distinct or occasionally connate, while those on the pedicels are smaller. The calyx is 2–5(6)-lobed, measuring 23–28 mm in total length, with individual lobes 21–25 mm long, oblanceolate, and pubescent; the calyx may be deciduous or persistent in fruit. The corolla is 25–27 mm long and pubescent. There are five stamens inserted about halfway up the corolla tube: the two upper stamens are fertile and coherent, positioned in the throat of the corolla tube, while the remaining three are staminodial with partially or fully abortive anthers. The fertile anthers are dithecal and dehisce either by longitudinal slits or occasionally by apical pores. The fruit is a fleshy or firm berry that may be ovoid, ellipsoid to cylindrical, or occasionally subglobose, and is often tipped with a persistent stylar beak. The seeds are narrowly ellipsoid, occasionally somewhat irregular, approximately 0.35 mm long, and pale reddish-brown with darker tips at both ends. These seeds have an inconspicuously reticulate surface.